The well-known conspiracy theory of the Philadelphia Experiment is widely considered a hoax. Still, conspiracy theorists have latched onto this tale for decades. It began in the 1940s with a letter from a person named Carlos Allende. Allende claimed he was aboard the U.S. Navy ship the USS Furuseth when he saw the USS Eldridge disappear and reappear right before his eyes-he called this the Philadelphia Experiment. He claimed that this was evidence that Albert Einstein had solved the unified field theory and that the U.S. government was secretly using this knowledge to experiment with teleportation and invisibility.